This invention relates to grapple for releasable attachment to the manipulating arm of a vehicle.
Vehicles for lifting and moving heavy objects are well known. Such vehicles, which include tractors, lifters and loaders, generally rely on hydraulically operated manipulator arms to which a tool is releasably attached. The tool can include equipment such as buckets, scraping blades, grapples or any other attachment capable of manipulating a desired object.
Of particular interest are grapples which generally include pivoting fingers to grasp and hold objects. Grapples are particularly useful for working with cylindrical objects such as drums, large paper rolls, logs, or pipes of various diameters. Examples of prior art grapple tools are disclosed in the following patents:
U.S. Pat. No. 3,038,620 to Collin
U.S. Pat. No. 3,527,495 to Maradyn et al.
U.S. Pat. No. 5,118,248 to Brucher
U.S. Pat. No. 5,536,133 to Velez et al.
A desirable feature of grapples, particularly when working with rolls or drums, is the ability to re-orient the grapple when grasping an object so that the object can be rotated. It is desirable to be able to rotate grasped cylindrical drums or rolls about their longitudinal axis through 90 degrees to rotate them from their planar ends to their cylindrical sides or through 180 degrees to flip them end for end. Preferably, the grapple can rotate through 360 degrees to allow the operator to select either clockwise or counterclockwise rotation of an object for maximum efficiency of manipulation.
The grapples disclosed in the above patents all use various mechanisms to rotate the grasping fingers and the held object. The equipment tends to rely on complex gearing and bearing mechanisms that involve many parts and are expensive to manufacture.
I have developed a novel grapple unit of simple construction that is capable of reliably grasping, lifting and re-orienting objects through 360 degrees or less.
Accordingly, the present invention provides a grapple for releasable attachment to a manipulator arm of a vehicle comprising:
a central framework;
a pair of spaced, opposed gripping fingers pivotally connected to the central framework to define a grasping region between the fingers, the fingers being movable to open and close the grasping region;
a joint assembly adapted to rotatably mount the central framework to the manipulator arm comprising a first planar bearing surface releasably connectable to the manipulator arm, a second planar bearing surface formed on the central framework and extending parallel to the first planar bearing surface, a sheet of low friction material inserted between the parallel bearing surfaces and engaging both surfaces, and a shaft intersecting the bearing surfaces to define an axis for rotation of the central framework with respect to the first planar bearing surface; and
a drive mechanism for controlling rotation of the central framework with respect to the first planar bearing surface.
The grapple of the present invention employs a unique joint assembly that is designed to spread loading over the surface of the sheet of low friction material.
The grapple of the present invention is particularly useful for moving and stacking barrels and drums, and handling of pipes, poles, logs, branches and miscellaneous debris. It is useful for manipulating large, heavy objects.